1. Field of the Invention
This disclosure relates to an Inter-UE Transfer (IUT).
2. Background of the Invention
In general, a session between a first terminal and a service provider, or between the first terminal and a second terminal in a network based upon an Internet Protocol (IP) Multimedia Subsystem (MS) (IMS) is performed under control of an application server.
Recently, as users use various types of plural terminals (for example, portable terminals, TVs, computers, smart phones, etc.), a research has been devoted to the technique for transferring/copying part or all of media flows composing a session, which was established by a first terminal, to a second terminal.
The transfer, move or copy of part or all of media flows in a session between terminals is referred to as Inter-UE Transfer (IUT).
The IUT may also be performed between terminals belonging to different users, as well as being performed between terminals belonging to same user, which has recently been researched in 3GPP Release 10. Consequently, information share, collaboration and entertainment between family members, business members and social network members are allowed by virtue of the IUT. The IUT will be described with reference to FIG. 1.
FIG. 1 is an overview showing an Inter-UE Transfer (IUT) according to the related art.
As shown in the left side of FIG. 1(a), a first user possesses a plurality of terminals, e.g., User Equipment (UE)-1, UE-2 and UE-3. The UE-1 owned by the first user has a session containing audio and video media with a remote end, for example, a service provider. FIG. 1 shows a Service Centralization and Continuity Application Server (SCC AS), which controls such session.
Under the environments, the first user desires to use the UE-2 and UE-3, respectively to perform the session with the remote end. For example, if it is assumed that the UE-1 is a cellular phone, the UE-2 is an earset or headset having a communication function, and the UE-3 is a Head Up Display (HUD) having a communication function, the first user desires to perform the audio media session with the remote end via the earset or headset, and perform the video media session with the remote end via the HUD.
Accordingly, as shown in the right side of FIG. 1(a), the audio media flow which was terminated to the UE-1, is transferred to the UE-2 and the video media flow thereof is transferred to the UE-3. Here, even after the audio and video media flows are transferred from the UE-1 to the UE-2 and UE-3, respectively, the UE-1 can still control the transferred audio and video media flows.
Here, the UE-1 is called as a controller UE and the UE-2 and the UE-3 are called as controllee UEs. Also, the session, which contains the audio and video media and in which the UE-1, UE-2 and UE-3 take part, is referred to as a collaborative session.
Meanwhile, as shown in the left side of FIG. 1(b), the first user is performing a session containing audio media flow using the UE-2 and is performing a session containing video media flow using the UE-3, and these media flows are under control of the UE-1. Here, the first user transfers the control (control-ownership) taken by the UE-1 to the UE-2.
Accordingly, as shown in the right side of FIG. 1(b), the UE-2 is performing the session containing the audio media flow, and has the control for the collaborative session in which the UE-2 and UE-3 are involved. The UE-3 keeps performing the session containing the video media flow. After the transfer of the control, UE-2 becomes a controller UE, and UE-3 is a controllee UE as the same as before, UE-1 no more belongs to the collaborative session.
On the other hand, as shown in the left side of FIG. 1(c), the first user is performing a session containing audio and video media flows with the remote end via the UE-1. Here, the first user transfers both the audio and video media flows and the control to the UE-3.
As shown in the right side of FIG. 1(c), the UE-3 accordingly performs the session containing the audio and video media flows. In this inter-UE transfer, no collaborative session is established.
FIG. 2 shows an IUT process according to the related art.
It is assumed in FIG. 2 that UE-1 11 and UE-2 12 belong to a user A, and UE-3 13 belongs to a user B.
FIG. 2 also shows a home network in which the users have subscribed. The home network includes IP Multimedia Subsystem (IMS) nodes 51, SCC AS-1 52a and SCC AS-2 52b. 
As shown in FIG. 2, in a state where the user A is performing a session containing text, audio and video media with the remote end 30 via the UE-1 11, the user A transfers the audio and video media flows to the UE-3 13 belonging to the user B while maintaining the session continuity. Here, even after the audio and video media flows are transferred to the UE-3 13, the UE-1 11 still has the control for the transferred media flows, which will be described in detail with reference to FIG. 2.
1) The UE-1 11 decides to transfer the audio and video media flows to the UE-3 13.
2a˜2b) The UE-1 11 sends a transfer request message, for example, Media Transfer Request message, to the SCC AS-1 52a to transfer the audio and video media flows to the UE-3 13.
3) The SCC AS-1 52a then authorizes or verifies the transfer request message sent by the UE-1 11. The authorization and verification may be performed based upon subscriber information. The authorization and verification may be performed to determine whether the UE-1 11 is a terminal for which the IUT operation is supported (allowed). Alternatively, the authorization or verification may be performed to determine whether the media flows in the UE-1 11 can be transferred to the UE-3 13.
4) The SCC AS-1 52a transfers the transfer request message to the SCC AS-2 52b via the IMS nodes 51.
5) The SCC AS-2 52b authorizes or verifies the transfer request message. The authorization or verification may be performed based upon subscriber information, which is similar to the foregoing description, so it will be understood by the foregoing description without detailed description.
6a˜6b) The SCC AS-2 52b sends a session initiation request message (for example, SIP-based INVITE message), which includes information related to the audio and video media flows requested to be transferred, to the UE-3 13 via the IMS nodes, in response to the transfer request message.
7a˜7b) The UE-3 13 then sends a session initiation accept message to the SCC AS-2 52b via the IMS nodes 51, in response to the session initiation request message.
8) The SCC AS-2 52b then forwards the session initiation accept message to the SCC AS-1 52a via the IMS nodes 51.
9) The SCC AS-1 52a completes the transfer of the audio and video media flows from the UE-1 11 to the UE-3 13 based upon the session initiation accept message.
The UE-1 11 has the control for a collaborative session containing the text media, the audio media and the video media, after transferring the audio and video media flows to the UE-3 13. That is, the UE-1 11 then serves as a controller UE, and the UE-3 13 serves as a controllee UE.
FIG. 3 is an exemplary view showing problems of the related art.
As shown in FIG. 3, UE-1 11 and UE-2 12 belong to a user A, and UE-3 13 belongs to a user B.
Also, FIG. 3 shows a home network in which the users A and B have subscribed. The home network includes IMS nodes 51, SCC AS-1 52a and SCC AS-2 52b. 
1˜2) The UE-1 11 sends a registration request to the IMS nodes 51 to register in its home network, and receives an acknowledgement message. Here, the registration informs the home network of the UE-1 11's current location.
3˜4) The IMS nodes 51 then perform a third-party registration for the UE-1 to SCC AS-1 52a, which serves the UE-1 11, and receives an acknowledgement message therefrom.
5a˜5d) When the UE-1 11 sends a session initiation request message to establish a session containing audio and video media with a remote end 30, the IMS nodes 51 then forward the session initiation request message to the SCC AS-1 52a serving the UE-1 11 based upon subscriber information of the user A. The SCC AS-1 52a then transfers the session initiation request message to the remote end 30 via the IMS nodes 51.
6a˜6d) The remote end 30 sends a session initiation accept message to the IMS nodes 51, and the IMS nodes 51 forward it to the SCC AS-1 52a. The SCC As-1 52a then transfers the session initiation accept message to the UE-1 11 via the IMS nodes 51. Accordingly, the session containing the audio and video media is established between the UE-1 11 and the remote end 30.
7˜8) Meanwhile, the user A desires to transfer some media of the session or control for the session from the UE-1 11 to the UE-2 12, and thus manipulates the UE-2 12. However, the UE-2 12 has no information related to the session being performed by the UE-1 11 (for example, the UE-2 12 cannot know which media flows are ongoing on the UE-1), and thus it may not decide which media flows can be taken from the UE-1 11. Hence, the UE-2 12 cannot generate and send a transfer request message.
9˜10) Also, the user B desires to transfer some media of the session or the control for the session from the UE-1 11 to the UE-3 13, and thus manipulates the UE-3 13. However, the UE-3 13 has no information related to the session being performed by the UE-1 11 (for example, the UE-3 13 cannot know which media flows are ongoing on the UE-1), and thus it may not decide which media flows can be taken from the UE-1 11. Hence, the UE-3 13 cannot generate and send a transfer request message.